Studies on ionic transport induced by carriers and channels are proposed to further understanding of the molecular factors underlying ion permeation, voltage gating and anomalous rectification in membranes of excitable cells, such as nerve, muscle and heart. Known variations in the structure of ion selective carriers will be related to changes of the electrical properties they induce in membranes. Emphasis will be placed on those features of permeation that are common to both carriers and channels, such as loading and unloading of ions, and the rate constants for their kinetics will be evaluated. A class of calcium-carrier antibiotics will also be characterized, and theoretical studies will be extended to encompass the effects of diffusion-coupled ion-carrier homogeneous reactions. In addition, "anomalous" rectification will be investigated theoretically and experimentally. Previously formulated models for the macroscopic steady-state properties will be developed to encompass the expected time-dependent kinetics and the power spectral density. Experimental studies, using voltage-clamp and noise analysis methods, will be carried out on the rectifying membranes of egg cells for the twofold objective of testing the predictions of the models and further characterizing the membrane properties in sufficient detail to resolve single channel conductances and the kinetics of "gating".